The invention relates generally to power-driven conveyors and more particularly to accumulators comprising a series of in-line roller belts.
Roller belts with in-line rollers, i.e., rollers mounted on axles or hinge rods forming axes of rotation perpendicular to the direction of belt travel, are used to allow blocked articles, such as boxes or packages, to accumulate atop the rollers as the roller belt continues to advance. The rollers rotate freely about their axes of rotation as they advance with the belt under the accumulating articles. Because of the rolling contact with the bottoms of the articles, the articles accumulate on the belt with low back line pressure. In many roller-belt conveyors, the belt rollers can be actuated, when not accumulating, by contact with a roller-actuating surface in the belt's carryway. When actuated, the belt rollers propel articles atop the actuated rollers forward along the advancing belt. With the rollers actuated, the belt is in low-friction rolling contact with the carryway. But when the rollers are deactuated to rotate freely during accumulation, the belt is supported in sliding contact with the carryway. Because sliding friction is much greater than rolling friction, the belt's drive motor has to be sized considerably larger to accommodate a fully loaded and deactuated roller belt.